Effect of black liquor carryover on selectivity of oxygen delignification - Brownstock washing plays a major role

Carryover can be a problem at pulp mills if brownstock washing is inadequat e. Because of the residual alkali present in black liquor and the exotherma l oxidation reaction, the temperature in the oxygen delignification tower c an increase and thus accelerate unselective reactions in the fibre. A labor atory study was conducted on Finnish softwood brownstock to determine the l evel of carryover-containing black liquor that adversely affects softwood p ulp under oxygen delignification conditions and lowers the efficiency of ox ygen delignification.